Setting up webdav on mybooklive is fairly easy because apache2 supports it natively and there is nothing you have to install. I use webdav across SSL so that my Apple iPad can access presentations from keynote directly from MBL versus a 3rd party service. You can mount the folder as a web drive as well and access externally. When finished, you will be able to access your files at:

Create new passwd file called passwd.dav with username webdav:
# htpasswd -c /etc/apache2/passwd.dav webdav
(note that this is quite basic password authentication. More secure methods exist but I don't have experience in using them).

Enable our new web site:
# a2ensite default-ssl

Test your new config with this command:
# apache2ctl configtest

If there are no errors then continue and restart apache2 (otherwise check your edits to default-ssl:
# /etc/init.d/apache2 reload

Then when you get here, type ls to list everything inside /var/www/webdav
dav:/webdav/> ls

To complete this tutorial, I prefer my files are stored in a separate folder that I can access also from my PC as a share. (i.e. samba)

# cd /var/www
(remove dir webdav if you created it)
# rmdir webdav
# mkdir /nfs/Public/webdav
# ln –s /nfs/Public/webdav .
Set permissions so that any file created by WebDav can also be read by a PC through samba:

# echo “umask 002" » /etc/apache2/envars
(will make apache2 write 664 as www-data, most important is that group must be read-write)

set gid so that all files created by webdav or your PC will be with the same group “share”:
# chgrp w+s /nfs/Public/webdav

(2) Create new passwd file called passwd.dav with username webdav:
# htpasswd -c /etc/apache2/passwd.dav webdav
(note that this is quite basic password authentication. More secure methods exist but I don't have experience in using them).

(3) needed to have the Basic Authentication module enabled in the LoadModules section of the httpd.conf
# nano /etc/apache2/httpd.conf

I propose the simplest way and secure in my opinion adding a new user/pass in wd2go user list.
wd2go uses Webdav but even if we can know the users, we don't have the user's pass they have selected.
So you have to create at least one new user/pass :

I did use bourgeoa's updated method (see link below, pretty similar to the original one I think) but cannot access my shares remotely with http or https : //<external_IP>/AnyOfYourShare… In fact, when using https, I get a security warning that tells me I am redirected to a server named something like *.123456device.wd2go.com. That is before getting asked for user/password.

Since it seems it worked for you and you are still around, any idea what to do to fix this ? Have you experienced the same or do other prerequisite mods I should do first ?